CODIS vs. Genealogy DNA Databases

There has been much discussion lately about law enforcement using public DNA databases that consumers use for genealogy. In the past, law enforcement was limited to their own databases of DNA profiles. Since law enforcement already has their own databases that contain DNA profiles what is the big deal? What purpose do genealogy databases serve for law enforcement if they already have their own databases?

CODIS is short for Combined DNA Index System which is the national system used for DNA profile storage and indexing that was created by the FBI. The National DNA Index system (NDIS) is the part of CODIS that contains DNA profiles submitted by forensic labs. These DNA profiles are indexed into several databases for use by law enforcement agencies. The existence of a national DNA databases provides law enforcement the means to upload and share DNA profiles between agencies.

Where do CODIS DNA Profiles Come From?

Law enforcement agencies across the country collect DNA samples to aid in identification of appropriate individuals. Each state has its own DNA databases and regulations regarding DNA collection, processing and what DNA is included in their database. The regulations each state follows is not necessarily the same as those used for CODIS. However, the profiles accepted for indexing in CODIS must meet requirements for inclusion in the national database.

The DNA Identification Act of 1994 regulates who can participate in CODIS, what information and whose information can be held in the database. Regardless of where the DNA sample originated from it must be processed by a lab that is authorized to participate in CODIS. Participating labs must be accredited by a professional nonprofit association that is nationally recognized in the forensic science community. They must also comply with all regulations regarding CODIS labs.

What is a Genealogy DNA Database?

Recording our family histories is nothing new. We all want to track who we are and where we have come from. What is relatively new is the abundance of resources available to us now to help us find information about our ancestors. We have access to countless databases of newspapers, church records, books and other information that can help us find information about people in our family tree and find family members that we were not aware of. We can save these records on genealogy websites and share them with others who can use them to fill in gaps in their own family trees. DNA is now another resource that can be gathered, analyzed and shared by amateur and professional genealogists.

Anyone can now spit into a tube and have their own unique DNA profile created by consumer genetic genealogy labs. These profiles are uploaded into a database and compared to other profiles. This process can identify which profiles belong to members of the same family line as far back as fifth cousins. Unless the match is a close relative it can not necessarily place these distant relatives in exact locations on your family tree but with a bit of genealogical investigative work, professional genealogists can do just that.

The databases which consumer DNA profiles are added to are private and not generally available to law enforcement. However, people are free to upload their unique DNA profiles to public databases.  By uploading a DNA profile to public databases the pool of possible relatives becomes much larger so a person can broaden their search for distant relatives. Public databases are accessible to everyone.

At the time of this post the only known public DNA database is GEDmatch. However, there is also a consumer based DNA database that allows their members to opt into being able to be matches with law enforcement investigations. That consumer company is Family Tree DNA.

Why are genealogy DNA databases beneficial to law enforcement?

The DNA Identification Act of 1994 limits whose DNA profiles can be uploaded to CODIS. There are several categories of inclusion in national databases such as convicts, arrestees and missing persons. What genetic information can be stored in the national database is also restricted. CODIS is intended to match DNA profiles that have already been uploaded with newly submitted profiles. The intent of CODIS is to find exact profile to profile matches although sometimes partial matches are obtained.

The DNA profiles in the NDIS do not contain information that could link the profile with an actual person. Genetic information within CODIS is safeguarded and only authorized personnel are allowed to access the database. Once a DNA match is found in CODIS the local law enforcement agency and lab that submitted the profile must be contacted to obtain information about who that profile belongs to. Once the source of the CODIS profile is identified a warrant can be issued to perform DNA testing to confirm the match.

Frequently there is no DNA profile in CODIS that provides a match. This is when genealogy DNA databases can become useful to the law enforcement community. Unlike CODIS, DNA profiles produced by labs for genealogical purposes are intended to identify possible relatives, not just exact matches. These profiles are more complex and contain a lot more genetic information about the subject. A much larger portion of the population becomes subject to these searches through samples submitted by their distant relatives.

When a CODIS profile matches with a newly submitted sample the producing lab and local law enforcement agency where the profile originated identify who the profile belongs to. Familial matches obtained through genealogical DNA profiles do not identify an exact sample to sample match. Instead, genealogists must use their investigative skills to build a family tree and identify where the profile likely originated from. Genealogists are able to narrow down the possible subjects considerably and law enforcement can use this information to obtain DNA for further testing to prove an exact match.

Countless violent crimes with DNA evidence have remained unsolved because there was not an exact match within the CODIS database. Genealogy DNA databases allow law enforcement the ability to exponentially broaden their scope in hopes of solving even the coldest of cases.